Exhibit 10.3
    

    
      THE SECURITIES REPRESENTED HEREBY MAY NOT BE TRANSFERRED UNLESS (I) SUCH
      SECURITIES HAVE BEEN REGISTERED FOR SALE PURSUANT TO THE SECURITIES ACT
      OF 1933, AS AMENDED, (II) SUCH SECURITIES MAY BE SOLD PURSUANT TO RULE
      144, OR (III) THE COMPANY HAS RECEIVED AN OPINION OF COUNSEL REASONABLY
      SATISFACTORY TO IT THAT SUCH TRANSFER MAY LAWFULLY BE MADE WITHOUT
      REGISTRATION UNDER THE SECURITIES ACT OF 1933 OR QUALIFICATION UNDER
      APPLICABLE STATE SECURITIES LAWS. NOTWITHSTANDING THE FOREGOING, THE
      SECURITIES MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT
      SECURED BY THE SECURITIES
    

    
      SUBJECT TO THE PROVISIONS OF SECTION 10 HEREOF, THIS WARRANT SHALL BE
      VOID AFTER 5:00 P.M. EASTERN TIME ON AUGUST 11, 2012, (THE “EXPIRATION
      DATE”).
    

    
    	
          
            No. F-_______
          

        	
          
            August 11, 2008
          

        


    

    
      OPEXA THERAPEUTICS, INC.
SERIES
      F WARRANT TO PURCHASE ________
      SHARES OF
COMMON STOCK,
      PAR VALUE $0.50 PER SHARE
    

    
      For VALUE RECEIVED, _______________(“Warrantholder”), is entitled
      to purchase, subject to the provisions of this Series F Warrant (the
      “Warrant”), from Opexa Therapeutics, Inc., a Texas corporation
      (“Company”), at any time from and after the date six months after the
      date hereof (the “Initial Exercise Date”) and not later than 5:00 P.M.,
      Eastern time, on the Expiration Date (as defined above), at an exercise
      price per share equal to $1.78 (the exercise price in effect being
      herein called the “Warrant Price”), ________ shares
      (“Warrant Shares”) of the Company’s Common Stock, par value $0.50 per
      share (“Common Stock”).  The number of Warrant Shares purchasable upon
      exercise of this Warrant and the Warrant Price shall be subject to
      adjustment from time to time as described herein.
    

    
      This Warrant is one of a series of Series F Warrants of like tenor
      issued by the Company pursuant to that certain Unit Purchase Agreement
      dated August 8, 2008, among the Company and the Investors named therein
      (the “Purchase Agreement”), and initially covering an aggregate of up to ________  shares
      of Common Stock (collectively, the “Company Warrants”).
    

    
      Section 1.  Registration.  The Company shall maintain
      books for the transfer and registration of the Warrant.  Upon the
      initial issuance of this Warrant, the Company shall issue and register
      the Warrant in the name of the Warrantholder.
    

    
      Section 2.  Transfers.  As provided herein, this
      Warrant may be transferred only pursuant to a registration statement
      filed under the Securities Act of 1933, as amended (the “Securities
      Act”), or an exemption from such registration.  Subject to such
      restrictions, the Company shall transfer this Warrant from time to time
      upon the books to be maintained by the Company for that purpose, upon
      surrender hereof for transfer, properly endorsed or accompanied by
      appropriate instructions for transfer and such other documents as may be
      reasonably required by the Company, including, if required by the
      Company, an opinion of its counsel to the effect that such transfer is
      exempt from the registration requirements of the Securities Act, to
      establish that such transfer is being made in accordance with the terms
      hereof, and a new Warrant shall be issued to the transferee and the
      surrendered Warrant shall be canceled by the Company.
    

    
      
        

        

      

      
        
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      Section 3.  Exercise of Warrant.  
    

    
         (a)  Subject to the provisions hereof, the Warrantholder may exercise
      this Warrant, in whole or in part, at any time after the Initial
      Exercise Date and prior to its expiration upon surrender of the Warrant,
      together with delivery of a duly executed Warrant exercise form, in the
      form attached hereto as Appendix A (the “Exercise Agreement”) and
      payment by cash, certified check or wire transfer of funds, or pursuant
      to a cashless exercise pursuant to Section3(b) below, of the aggregate
      Warrant Price for that number of Warrant Shares then being purchased, to
      the Company during normal business hours on any business day at the
      Company’s principal executive offices (or such other office or agency of
      the Company as it may designate by notice to the Warrantholder).  The
      Warrant Shares so purchased shall be deemed to be issued to the
      Warrantholder or the Warrantholder’s designee, as the record owner of
      such shares, as of the close of business on the date on which this
      Warrant shall have been surrendered (or the date evidence of loss, theft
      or destruction thereof and security or indemnity satisfactory to the
      Company has been provided to the Company), the Warrant Price shall have
      been paid and the completed Exercise Agreement shall have been
      delivered.  Certificates for the Warrant Shares so purchased shall be
      delivered to the Warrantholder within a reasonable time, not exceeding
      three (3) business days, after this Warrant shall have been so
      exercised.  The certificates so delivered shall be in such denominations
      as may be requested by the Warrantholder and shall be registered in the
      name of the Warrantholder or such other name as shall be designated by
      the Warrantholder, as specified in the Exercise Agreement.  If this
      Warrant shall have been exercised only in part, then, unless this
      Warrant has expired, the Company shall, at its expense, at the time of
      delivery of such certificates, deliver to the Warrantholder a new
      Warrant representing the right to purchase the number of shares with
      respect to which this Warrant shall not then have been exercised.  As
      used herein, “business day” means a day, other than a Saturday or
      Sunday, on which banks in Houston, Texas are open for the general
      transaction of business.  Each exercise hereof shall constitute the
      re-affirmation by the Warrantholder that the representations and
      warranties contained in Section 5 of the Purchase Agreement are true and
      correct in all material respects with respect to the Warrantholder as of
      the time of such exercise.  Notwithstanding the foregoing, to effect the
      exercise of the Warrant hereunder, the Warrantholder shall not be
      required to physically surrender this Warrant to the Company unless the
      entire Warrant is exercised.  The Warrantholder and the Company shall
      maintain records showing the amount exercised and the dates of such
      exercise.  The Warrantholder and any assignee, by acceptance of this
      Warrant, acknowledge and agree that, by reason of the provision of the
      paragraph, following exercise of a portion of the Warrant, the number of
      Warrant Shares of this Warrant may be less than the amount stated on the
      face hereof.  
    

    
         (b)  Subject to the provisions hereof, the Warrantholder may effect
      one or more cashless exercises by surrendering Warrants to the Warrant
      Agent and giving written notice that the Warrantholder wishes to effect
      a cashless exercise by surrendering some Warrants without exercise, upon
      which the Company shall issue, or cause to be issued, to the
      Warrantholder up to the number of Warrant Shares determined as follows:
    

    
      
        

        

      

      
        
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      X         =         Y x (A-B)/A
    

    
      where:
    

    
      X         =         the maximum number of Warrant Shares that may be
      issued to the Warrantholder;
    

    
      Y         =         the number of Warrant Shares with respect to which
      the Warrant Certificates are being exercised;
    

    
      A         =         the Market Price as of the Date of Exercise; and
    

    
      B         =         the Exercise Price.
    

    
      “Market Price” of a share of Common Stock on any date shall mean, (i) if
      the shares of Common Stock are traded on the Nasdaq Global Market or
      Nasdaq Capital Market, the last bid price reported on that date; (ii) if
      the shares of Common Stock are no longer quoted on Nasdaq and are listed
      on any other national securities exchange, the last sale price of the
      Common Stock reported by such exchange on that date; (iii) if the shares
      of Common Stock are not quoted on a any such market or listed on any
      such exchange and the shares of Common Stock are traded in the
      over-the-counter market, the last price reported on such day by the OTC
      Bulletin Board; (iv) if the shares of Common Stock are not quoted on a
      any such market, listed on any such exchange or quoted on the OTC
      Bulletin Board, then the last price quoted on such day in the
      over-the-counter market as reported by the National Quotation Bureau
      Incorporated (or any similar organization or agency succeeding its
      functions of reporting prices); or (v) if none of clauses (i)-(iv) are
      applicable, then as determined by mutual agreement of the Company and
      the Warrantholder; or if the Company and the Warrantholder are unable to
      agree on a Market Price, either party may submit the matter to
      arbitration as provided in Section 17.
    

    
      “Date of Exercise” means the date on which the Company has received from
      Warrantholder (i) the Warrant, and (ii) a written notice of election to
      exercise signed by Warrantholder and indicating the number of Warrant
      Shares to be purchased.
    

    
      This rights granted herein shall not in any way limit any other remedies
      that a Warrantholder may have under the Registration Rights Agreement
      (the “Registration Rights Agreement”) or in any other agreement or any
      other remedies that may be available pursuant to applicable law for
      breach by the Company of the Registration Rights Agreement.
    

    
      
        

        

      

      
        
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         (c)  Company’s Failure to Timely Deliver
      Securities.  If within three (3) Trading Days after the Company’s
      receipt of the facsimile copy of an Exercise Notice the Company shall
      fail to issue and deliver a certificate to the Warrantholder and
      register such shares of Common Stock on the Company’s share register or
      credit the Warrantholder’s balance account with DTC for the number of
      shares of Common Stock to which the Warrantholder is entitled upon the
      Warrantholder’s exercise hereunder or pursuant to the Company’s
      obligation set forth in clause (ii) below, and if on or after such
      Trading Day the Warrantholder purchases (in an open market transaction
      or otherwise) shares of Common Stock to deliver in satisfaction of a
      sale by the Warrantholder of shares of Common Stock issuable upon such
      exercise that the Warrantholder anticipated receiving from the Company
      (a “Buy-In”), then the Company shall, within three (3) Business Days
      after the Warrantholder’s request and in the Warrantholder’s discretion,
      either (i) pay cash to the Warrantholder in an amount equal to the
      Warrantholder’s total purchase price (including brokerage commissions,
      if any) for the shares of Common Stock so purchased (the “Buy-In
      Price”), at which point the Company’s obligation to deliver such
      certificate (and to issue such shares of Common Stock) or credit such
      Warrantholder’s balance account with DTC shall terminate, or (ii)
      promptly honor its obligation to deliver to the Warrantholder a
      certificate or certificates representing such shares of Common Stock or
      credit such Warrantholder’s balance account with DTC and pay cash to the
      Warrantholder in an amount equal to the excess (if any) of the Buy-In
      Price over the product of (A) such number of shares of Common Stock,
      times (B) the Market Price on the date of exercise.
    

    
         (d)  [Beneficial Ownership.  The
      Company shall not effect the exercise of this Warrant, and the
      Warrantholder shall not have the right to exercise this Warrant, to the
      extent that after giving effect to such exercise, such Person (together
      with such Person’s affiliates) would beneficially own in excess of 9.99%
      (the “Maximum Percentage”) of the shares of Common Stock outstanding
      immediately after giving effect to such exercise.  For purposes of the
      foregoing sentence, the aggregate number of shares of Common Stock
      beneficially owned by such Person and its affiliates shall include the
      number of shares of Common Stock issuable upon exercise of this Warrant
      with respect to which the determination of such sentence is being made,
      but shall exclude shares of Common Stock which would be issuable upon
      (A) exercise of the remaining, unexercised portion of this Warrant
      beneficially owned by such Person and its affiliates and (B) exercise or
      conversion of the unexercised or unconverted portion of any other
      securities of the Company beneficially owned by such Person and its
      affiliates (including, without limitation, any convertible notes or
      convertible preferred stock or warrants) subject to a limitation on
      conversion or exercise analogous to the limitation contained
      herein.  Except as set forth in the preceding sentence, for purposes of
      this paragraph, beneficial ownership shall be calculated in accordance
      with Section 13(d) of the Securities Exchange Act of 1934, as amended
      (the “1934 Act”).  For purposes of this Warrant, in determining the
      number of outstanding shares of Common Stock, the Warrantholder may rely
      on the number of outstanding shares of Common Stock as reflected in (1)
      the Company’s most recent Form 10-K, Form 10-Q, Current Report on Form
      8-K or other public filing with the Securities and Exchange Commission,
      as the case may be, (2) a more recent public announcement by the Company
      or (3) any other notice by the Company or the Transfer Agent setting
      forth the number of shares of Common Stock outstanding.  For any reason
      at any time, upon the written or oral request of the Warrantholder, the
      Company shall within one (1) Business Day confirm orally and in writing
      to the Warrantholder the number of shares of Common Stock then
      outstanding.  In any case, the number of outstanding shares of Common
      Stock shall be determined after giving effect to the conversion or
      exercise of securities of the Company, including the Warrants, by the
      Warrantholder and its affiliates since the date as of which such number
      of outstanding shares of Common Stock was reported.  By written notice
      to the Company, the Warrantholder may from time to time increase or
      decrease the Maximum Percentage to any other percentage not in excess of
      9.99% specified in such notice; provided that (i) any such increase will
      not be effective until the sixty-first (61st) day after such notice is
      delivered to the Company, and (ii) any such increase or decrease will
      apply only to the Warrantholder and not to any other holder of SPA
      Warrants.  The provisions of this paragraph shall be construed and
      implemented in a manner otherwise than in strict conformity with the
      terms of this Section 3(d) to correct this paragraph (or any portion
      hereof) which may be defective or inconsistent with the intended
      beneficial ownership limitation herein contained or to make changes or
      supplements necessary or desirable to properly give effect to such
      limitation.]1
    

    
      
        

        

      

      
        
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      Section 4.  Compliance with the Securities Act of 1933.
      Except as provided in the Purchase Agreement, the Company may cause the
      legend set forth on the first page of this Warrant to be set forth on
      each Warrant, and a similar legend on any security issued or issuable
      upon exercise of this Warrant, unless counsel for the Company is of the
      opinion as to any such security that such legend is unnecessary.
    

    
      Section 5.  Payment of Taxes.  The Company will pay any
      documentary stamp taxes attributable to the initial issuance of Warrant
      Shares issuable upon the exercise of the Warrant; provided, however,
      that the Company shall not be required to pay any tax or taxes which may
      be payable in respect of any transfer involved in the issuance or
      delivery of any certificates for Warrant Shares in a name other than
      that of the Warrantholder in respect of which such shares are issued,
      and in such case, the Company shall not be required to issue or deliver
      any certificate for Warrant Shares or any Warrant until the person
      requesting the same has paid to the Company the amount of such tax or
      has established to the Company’s reasonable satisfaction that such tax
      has been paid.  The Warrantholder shall be responsible for income taxes
      due under federal, state or other law, if any such tax is due.
    

    
      Section 6.  Mutilated or Missing Warrants.  In case
      this Warrant shall be mutilated, lost, stolen, or destroyed, the Company
      shall issue in exchange and substitution of and upon surrender and
      cancellation of the mutilated Warrant, or in lieu of and substitution
      for the Warrant lost, stolen or destroyed, a new Warrant of like tenor
      and for the purchase of a like number of Warrant Shares, but only upon
      receipt of evidence reasonably satisfactory to the Company of such loss,
      theft or destruction of the Warrant, and with respect to a lost, stolen
      or destroyed Warrant, reasonable indemnity or bond with respect thereto,
      if requested by the Company.
    

    
      Section 7.  Reservation of Common Stock.  At any time
      when this Warrant is exercisable, the Company shall at all applicable
      times keep reserved until issued (if necessary) as contemplated by this
      Section 7, out of the authorized and unissued shares of Common Stock, at
      least a number of shares of Common Stock equal to 120% of the number of
      shares of Common Stock as shall from time to time be necessary to effect
      the exercise of all of this Warrant then outstanding.  The Company
      agrees that all Warrant Shares issued upon due exercise of the Warrant
      shall be, at the time of delivery of the certificates for such Warrant
      Shares, duly authorized, validly issued, fully paid and non-assessable
      shares of Common Stock of the Company.
    

    
      Section 8.  Adjustments.  Subject and pursuant to the
      provisions of this Section 8, the Warrant Price and number of Warrant
      Shares subject to this Warrant shall be subject to adjustment from time
      to time as set forth hereinafter.
    

    
      _____________________
1 To be included only at the
      specific request of an Investor on the Signature Page of the Purchase
      Agreement.
    

    
      
        

        

      

      
        
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         (a)  If the Company shall, at any time or from time to time while
      this Warrant is outstanding, pay a dividend or make a distribution on
      its Common Stock in shares of Common Stock, subdivide its outstanding
      shares of Common Stock into a greater number of shares or combine its
      outstanding shares of Common Stock into a smaller number of shares or
      issue by reclassification of its outstanding shares of Common Stock any
      shares of its capital stock (including any such reclassification in
      connection with a consolidation or merger in which the Company is the
      continuing corporation), then (i) the Warrant Price in effect
      immediately prior to the date on which such change shall become
      effective shall be adjusted by multiplying such Warrant Price by a
      fraction, the numerator of which shall be the number of shares of Common
      Stock outstanding immediately prior to such change and the denominator
      of which shall be the number of shares of Common Stock outstanding
      immediately after giving effect to such change and (ii) the number of
      Warrant Shares purchasable upon exercise of this Warrant shall be
      adjusted by multiplying the number of Warrant Shares purchasable upon
      exercise of this Warrant immediately prior to the date on which such
      change shall become effective by a fraction, the numerator of which is
      shall be the Warrant Price in effect immediately prior to the date on
      which such change shall become effective and the denominator of which
      shall be the Warrant Price in effect immediately after giving effect to
      such change, calculated in accordance with clause (i) above.  Such
      adjustments shall be made successively whenever any event listed above
      shall occur.
    

    
         (b)  If  the Company at any time this Warrant is outstanding shall
      issue shares of Common Stock or “Common Stock Equivalents,” as defined
      below, entitling any person to acquire shares of Common Stock, at a
      price per share (determined in accordance with this Paragraph (b) below)
      less than the then current Warrant Price, then, the Warrant Price shall
      be reduced to equal the product of the then effective Warrant Price
      times a fraction determined as follows:
    

    
      (x)       the numerator of which shall be the number of shares of Common
      Stock outstanding immediately prior to such issuance plus the number of
      shares of Common Stock which the aggregate consideration received by the
      Company for the newly issued shares of Common Stock or Common Stock
      Equivalents would purchase at the then current Warrant Price, and
    

    
      (y)       the denominator of which shall be the number of shares of
      Common Stock outstanding immediately prior to such issuance plus the
      actual number of shares of Common Stock or Common Stock Equivalents
      newly issued.
    

    
      “Common Stock Equivalents” means any securities of the Company which
      would entitle the holder thereof to acquire at any time Common Stock,
      including without limitation, any debt, preferred stock, rights,
      options, warrants or other instrument that is at any time convertible
      into or exchangeable for, or otherwise entitles the holder thereof to
      receive, Common Stock.
    

    
      The Company shall notify the Holder in writing, no later than three (3)
      business days following the issuance of any Common Stock or Common Stock
      Equivalent subject to this section, indicating therein the applicable
      issuance price, or of applicable reset price, exchange price, conversion
      price and other pricing terms.
    

    
      
        

        

      

      
        
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      Notwithstanding the foregoing, the Warrant Price shall not be reduced
      below $1.53 unless such reduction is approved by the vote of a majority
      of the stockholders.
    

    
      If the Company shall in any manner grant (directly and not by assumption
      in a merger or otherwise) any warrants or other rights to subscribe for
      or to purchase, or any options for the purchase of, Common Stock or any
      stock or security convertible into or exchangeable for Common Stock
      (such warrants, rights or options being called “Options” and such
      convertible or exchangeable stock or securities being called
      “Convertible Securities”) whether or not such Options or the right to
      convert or exchange any such Convertible Securities are immediately
      exercisable, and the price per share for which Common Stock is issuable
      upon the exercise of such Options or upon the conversion or exchange of
      such Convertible Securities (determined by dividing (i) the sum (which
      sum shall constitute the applicable consideration) of (x) the total
      amount, if any, received or receivable by the Company as consideration
      for the granting of such Options, plus (y) the aggregate amount of
      additional consideration payable to the Company upon the exercise of all
      such Options, plus (z), in the case of such Options which relate to
      Convertible Securities, the aggregate amount of additional
      consideration, if any, payable upon the issue or sale of such
      Convertible Securities and upon the conversion or exchange thereof, by
      (ii) the total maximum number of shares of Common Stock issuable upon
      the exercise of such Options or upon the conversion or exchange of all
      such Convertible Securities issuable upon the exercise of such Options)
      shall be less than the Warrant Price in effect immediately prior to the
      time of the granting of such Options, then the total number of shares of
      Common Stock issuable upon the exercise of such Options or upon
      conversion or exchange of the total amount of such Convertible
      Securities issuable upon the exercise of such Options shall be deemed to
      have been issued for such price per share as of the date of granting of
      such Options or the issuance of such Convertible Securities and
      thereafter shall be deemed to be outstanding for purposes of adjusting
      the Warrant Price.  No adjustment of the Warrant Price shall be made
      upon the actual issue of such Common Stock or of such Convertible
      Securities upon exercise of such Options or upon the actual issue of
      such Common Stock upon conversion or exchange of such Convertible
      Securities.
    

    
      If the Company shall in any manner issue (directly and not by assumption
      in a merger or otherwise) or sell any Convertible Securities, whether or
      not the rights to exchange or convert any such Convertible Securities
      are immediately exercisable, and the price per share for which Common
      Stock is issuable upon such conversion or exchange (determined by
      dividing (i) the sum (which sum shall constitute the applicable
      consideration) of (x) the total amount received or receivable by the
      Company as consideration for the issue or sale of such Convertible
      Securities, plus (y) the aggregate amount of additional consideration,
      if any, payable to the Company upon the conversion or exchange thereof,
      by (ii) the total number of shares of Common Stock issuable upon the
      conversion or exchange of all such Convertible Securities) shall be less
      than the Warrant Price, as applicable, in effect immediately prior to
      the time of such issue or sale, then the total maximum number of shares
      of Common Stock issuable upon conversion or exchange of all such
      Convertible Securities shall be deemed to have been issued for such
      price per share as of the date of the issue or sale of such Convertible
      Securities and thereafter shall be deemed to be outstanding for purposes
      of adjusting the Warrant Price, provided that  no adjustment of the
      Warrant Price shall be made upon the actual issuance of such Common
      Stock upon conversion or exchange of such Convertible Securities and (b)
      no further adjustment of the Warrant Price shall be made by reason of
      the issue or sale of Convertible Securities upon exercise of any Options
      to purchase any such Convertible Securities for which adjustments of the
      Warrant Price have been made pursuant to the other provisions hereof.  
    

    
      
        

        

      

      
        
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      If the Company shall declare a dividend or make any other distribution
      upon any stock of the Company (other than the Common Stock) payable in
      Common Stock, Options or Convertible Securities, then any Common Stock,
      Options or Convertible Securities, as the case may be, issuable in
      payment of such dividend or distribution shall be deemed to have been
      issued or sold without consideration.
    

    
      If any shares of Common Stock, Options or Convertible Securities shall
      be issued or sold for cash, the consideration received therefor shall be
      deemed to be the net amount received by the Company therefor, after
      deduction therefrom of any expenses incurred or any underwriting
      commissions or concessions paid or allowed by the Company in connection
      therewith.  If any shares of Common Stock, Options or Convertible
      Securities shall be issued or sold for a consideration other than cash,
      the amount of the consideration other than cash received by the Company
      shall be deemed to be the fair market value of such consideration as
      determined jointly in good faith by the Board of Directors of the
      Company and the Warrantholder, after deduction of any expenses incurred
      or any underwriting commissions or concessions paid or allowed by the
      Company in connection therewith.  In case any Options shall be issued in
      connection with the issue and sale of other securities of the Company,
      together comprising one integral transaction in which no specific
      consideration is allocated to such Options by the parties thereto, such
      Options shall be deemed to have been issued for such consideration as
      determined jointly in good faith by the Board of Directors of the
      Company and the Warrantholder.  If Common Stock, Options or Convertible
      Securities shall be issued or sold by the Company and, in connection
      therewith, other Options or Convertible Securities (the “Additional
      Rights”) are issued, then the consideration received or deemed to be
      received by the Company shall be reduced by the fair market value of the
      Additional Rights (as determined jointly in good faith by the Board of
      Directors of the Company and the Warrantholder).
    

    
      Simultaneously with any adjustment to the Exercise Price pursuant to
      this Paragraph (b), the number of Warrant Shares that may be purchased
      upon exercise of this Warrant shall be increased or decreased
      proportionately, so that after such adjustment the aggregate Warrant
      Price payable hereunder for the adjusted number of Warrant Shares shall
      be the same as the aggregate Warrant Price in effect immediately prior
      to such adjustment
    

    
      Notwithstanding the foregoing, no adjustment will be made under this
      Paragraph (b) in respect of:  (i) the issuance of securities upon the
      exercise or conversion of any Common Stock Equivalents issued by the
      Company prior to the date hereof, (ii) Common Stock issued or deemed to
      be issued upon approval of a majority of the members of the Board of
      Directors of the Company or a majority of the members of a committee of
      directors established for such purpose, pursuant to options or similar
      awards to employees, directors, and consultants pursuant to any stock
      incentive plan, (iii) Common Stock issued or deemed to be issued to any
      bank or equipment lessor in connection with a financing or equipment
      lease, (iv) Common Stock issued or deemed to be issued pursuant to a
      “Strategic Transaction” approved by a majority of the Board of
      Directors.  A “Strategic Transaction” shall mean (x) any transaction
      with an acquiror, acquisition target company or merger partner, or (y) a
      joint venture, corporate alliance, research agreement or licensing
      transaction, but shall not include a transaction in which the Company is
      issuing securities primarily for the purpose of raising capital or to an
      entity whose primary business is investing in securities.
    

    
      
        

        

      

      
        
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         (c)  If any capital reorganization, reclassification of the capital
      stock of the Company, consolidation or merger of the Company with
      another corporation in which the Company is not the survivor, or sale,
      transfer or other disposition of all or substantially all of the
      Company’s assets to another corporation shall be effected, then, as a
      condition of such reorganization, reclassification, consolidation,
      merger, sale, transfer or other disposition, lawful and adequate
      provision shall be made whereby each Warrantholder shall thereafter have
      the right to purchase and receive upon the basis and upon the terms and
      conditions herein specified and in lieu of the Warrant Shares
      immediately theretofore issuable upon exercise of the Warrant, such
      shares of stock, securities or assets as would have been issuable or
      payable with respect to or in exchange for a number of Warrant Shares
      equal to the number of Warrant Shares immediately theretofore issuable
      upon exercise of the Warrant, had such reorganization, reclassification,
      consolidation, merger, sale, transfer or other disposition not taken
      place, and in any such case appropriate provision shall be made with
      respect to the rights and interests of each Warrantholder to the end
      that the provisions hereof (including, without limitation, provision for
      adjustment of the Warrant Price) shall thereafter be applicable, as
      nearly equivalent as may be practicable in relation to any shares of
      stock, securities or assets thereafter deliverable upon the exercise
      hereof.  The Company shall not effect any such consolidation, merger,
      sale, transfer or other disposition unless prior to or simultaneously
      with the consummation thereof the successor corporation (if other than
      the Company) resulting from such consolidation or merger, or the
      corporation purchasing or otherwise acquiring such assets or other
      appropriate corporation or entity shall assume the obligation to deliver
      to the Warrantholder, at the last address of the Warrantholder appearing
      on the books of the Company, such shares of stock, securities or assets
      as, in accordance with the foregoing provisions, the Warrantholder may
      be entitled to purchase, and the other obligations under this
      Warrant.  The provisions of this paragraph (b) shall similarly apply to
      successive reorganizations, reclassifications, consolidations, mergers,
      sales, transfers or other dispositions.
    

    
         (d)  In case the Company shall fix a payment date for the making of a
      distribution to all holders of Common Stock (including any such
      distribution made in connection with a consolidation or merger in which
      the Company is the continuing corporation) of evidences of indebtedness
      or assets (other than cash dividends or cash distributions payable out
      of consolidated earnings or earned surplus or dividends or distributions
      referred to in Section 8(a)), or subscription rights or warrants, the
      Warrant Price to be in effect after such payment date shall be
      determined by multiplying the Warrant Price in effect immediately prior
      to such payment date by a fraction, the numerator of which shall be the
      total number of shares of Common Stock outstanding multiplied by the
      Market Price per share of Common Stock immediately prior to such payment
      date, less the fair market value (as determined by the Company’s Board
      of Directors in good faith) of said assets or evidences of indebtedness
      so distributed, or of such subscription rights or warrants, and the
      denominator of which shall be the total number of shares of Common Stock
      outstanding multiplied by such Market Price per share of Common Stock
      immediately prior to such payment date.  
    

    
      
        

        

      

      
        
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         (e)  An adjustment to the Warrant Price shall become effective
      immediately after the payment date in the case of each dividend or
      distribution and immediately after the effective date of each other
      event which requires an adjustment.
    

    
         (f)  In the event that, as a result of an adjustment made pursuant to
      this Section 8, the Warrantholder shall become entitled to receive any
      shares of capital stock of the Company other than shares of Common
      Stock, the number of such other shares so receivable upon exercise of
      this Warrant shall be subject thereafter to adjustment from time to time
      in a manner and on terms as nearly equivalent as practicable to the
      provisions with respect to the Warrant Shares contained in this Warrant.
    

    
         (g)  To the extent permitted by applicable law and the listing
      requirements of any stock market or exchange on which the Common Stock
      is then listed, the Company from time to time may decrease the Warrant
      Price by any amount for any period of time if the period is at least
      twenty (20) days, the decrease is irrevocable during the period and the
      Board shall have made a determination that such decrease would be in the
      best interests of the Company, which determination shall be conclusive provided
      however, that the Warrant Price may not be decreased below the
      Market Price on the date of the execution of Purchase
      Agreement.  Whenever the Warrant Price is decreased pursuant to the
      preceding sentence, the Company shall provide written notice thereof to
      the Warrantholder at least five (5) days prior to the date the decreased
      Warrant Price takes effect, and such notice shall state the decreased
      Warrant Price and the period during which it will be in
      effect.  Notwithstanding the foregoing, the Company shall treat all
      holders of the Company Warrants equally.
    

    
      Section 9.  Fractional Interest.  The Company shall not
      be required to issue fractions of Warrant Shares upon the exercise of
      this Warrant.  If any fractional share of Common Stock would, except for
      the provisions of the first sentence of this Section 9, be deliverable
      upon such exercise, the Company, in lieu of delivering such fractional
      share, shall pay to the exercising Warrantholder an amount in cash equal
      to the Market Price (determined in accordance with Section 3(b)) of such
      fractional share of Common Stock on the date of exercise.
    

    
      Section 10.  Benefits.  Nothing in this Warrant shall
      be construed to give any person, firm or corporation (other than the
      Company and the Warrantholder) any legal or equitable right, remedy or
      claim, it being agreed that this Warrant shall be for the sole and
      exclusive benefit of the Company and the Warrantholder.
    

    
      Section 11.  Notices to Warrantholder.  Upon the
      happening of any event requiring an adjustment of the Warrant Price, the
      Company shall promptly give written notice thereof to the Warrantholder
      at the address appearing in the records of the Company, stating the
      adjusted Warrant Price and the adjusted number of Warrant Shares
      resulting from such event and setting forth in reasonable detail the
      method of calculation and the facts upon which such calculation is
      based.  Failure to give such notice to the Warrantholder or any defect
      therein shall not affect the legality or validity of the subject
      adjustment.
    

    
      Section 12.  Identity of Transfer Agent.  The Transfer
      Agent for the Common Stock is Continental Stock Transfer & Trust, 17
      Battery Place, New York, New York 10004.  Upon the appointment of any
      subsequent transfer agent for the Common Stock or other shares of the
      Company’s capital stock issuable upon the exercise of the rights of
      purchase represented by the Warrant, the Company will mail to the
      Warrantholder a statement setting forth the name and address of such
      transfer agent.
    

    
      
        

        

      

      
        
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      Section 13.  Notices.  Unless otherwise provided, any
      notice required or permitted under this Warrant shall be given in
      writing and shall be deemed effectively given and received as
      hereinafter described (i) if given by personal delivery, then such
      notice shall be deemed received upon such delivery, (ii) if given by
      telex or facsimile, then such notice shall be deemed received upon
      receipt of confirmation of complete transmittal, (iii) if given by
      certified mail return receipt requested, then such notice shall be
      deemed received upon the day such return receipt is signed, and (iv) if
      given by an internationally recognized overnight air courier, then such
      notice shall be deemed given one business day after delivery to such
      carrier.  Copies of such notices shall also be transmitted by email to
      the email address provided for on the signature page of the Purchase
      Agreement.  All notices shall be addressed as follows: if to the
      Warrantholder, at its address as set forth in the Company’s books and
      records and, if to the Company, at the address as follows, or at such
      other address as the Warrantholder or the Company may designate by ten
      days’ advance written notice to the other:
    

    
      If to the Company:
    

    
      Opexa Therapeutics, Inc.
2635 Crescent Ridge Drive
The Woodlands,
      Texas 77381
Attention:  Lynne Hohlfeld
Fax:  (281)
      872-8585
    

    
      With a copy to:
    

    
      Vinson & Elkins, LLP
First City Tower, 1001 Fannin Street, Suite
      2500
Houston, Texas 77002
Attention:  Michael C. Blaney
Fax:  (713)
      758-2222
    

    
      Section 14.  Registration Rights.  The initial
      Warrantholder (and its applicable assignees as provided in the
      Registration Rights Agreement) is entitled to the benefit of certain
      registration rights with respect to the shares of Common Stock issuable
      upon the exercise of this Warrant as provided in the Registration Rights
      Agreement.
    

    
      Section 15.  Successors.  All the covenants and
      provisions hereof by or for the benefit of the Warrantholder shall bind
      and inure to the benefit of its respective successors and assigns
      hereunder.
    

    
      Section 16.  Governing Law; Consent to Jurisdiction; Waiver
      of Jury Trial.  This Warrant shall be governed by, and construed in
      accordance with, the internal laws of the State of Texas, without
      reference to the choice of law provisions thereof.  The Company and, by
      accepting this Warrant, the Warrantholder, each irrevocably submits to
      the exclusive jurisdiction of the courts of the State of Texas located
      in Harris County and the United States District Court for the Southern
      District of Texas and the courts of the State of New York, Borough of
      Manhattan and the United States District Court for the Southern District
      of New York for the purpose of any suit, action, proceeding or judgment
      relating to or arising out of this Warrant and the transactions
      contemplated hereby.  Service of process in connection with any such
      suit, action or proceeding may be served on each party hereto anywhere
      in the world by the same methods as are specified for the giving of
      notices under this Warrant.  The Company and, by accepting this Warrant,
      the Warrantholder, each irrevocably consents to the jurisdiction of any
      such court in any such suit, action or proceeding and to the laying of
      venue in such court.  The Company and, by accepting this Warrant, the
      Warrantholder, each irrevocably waives any objection to the laying of
      venue of any such suit, action or proceeding brought in such courts and
      irrevocably waives any claim that any such suit, action or proceeding
      brought in any such court has been brought in an inconvenient forum.  EACH
      OF THE COMPANY AND, BY ITS ACCEPTANCE HEREOF, THE WARRANTHOLDER HEREBY
      WAIVES ANY RIGHT TO REQUEST A TRIAL BY JURY IN ANY LITIGATION WITH
      RESPECT TO THIS WARRANT AND REPRESENTS THAT COUNSEL HAS BEEN CONSULTED
      SPECIFICALLY AS TO THIS WAIVER.
    

    
      
        

        

      

      
        
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      Section 17.  Dispute Resolution.  In the case of a
      dispute as to the determination of the Market Price, the Company shall
      submit the disputed determinations via facsimile to the
      Warrantholder.  If the Warrantholder and the Company are unable to agree
      upon such determination of the Market Price within three business days
      of such disputed determination being submitted to the Warrantholder,
      then the Company shall, within two business days, submit via facsimile
      the disputed determination of the Market Price to an independent,
      reputable investment bank selected by the Company and approved by the
      Warrantholder.  The Company shall cause at its expense the investment
      bank to perform the determinations and notify the Company and the
      Warrantholder of the results no later than ten business days from the
      time it receives the disputed determinations or calculations.  Such
      investment bank's determination shall be binding upon all parties absent
      demonstrable error.
    

    
      Section 18.  No Rights as Stockholder.  Prior to the
      exercise of this Warrant, the Warrantholder shall not have or exercise
      any rights as a stockholder of the Company by virtue of its ownership of
      this Warrant.
    

    
      Section 19.  Amendment; Waiver.  Any term of this
      Warrant may be amended or waived (including the adjustment provisions
      included in Section 8 of this Warrant) upon the written consent of the
      Company and the holders of Series F Warrants representing at least 50%
      of the number of shares of Common Stock then subject to all outstanding
      Series F Warrants (the “Majority Holders”); provided,
      that (x) any such amendment or waiver must apply to all Series F
      Warrants; and (y) the number of Warrant Shares subject to this Warrant,
      the Warrant Price and the Expiration Date may not be amended, and the
      right to exercise this Warrant may not be altered or waived, without the
      written consent of the Warrantholder.
    

    
      
        

        

      

      
        
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      Section 20.  Remedies; Other Obligations; Breaches and
      Injunctive Relief.  The remedies provided in this Warrant shall be
      cumulative and in addition to all other remedies available under this
      Warrant and the other Transaction Documents, at law or in equity
      (including a decree of specific performance and/or other injunctive
      relief), and nothing herein shall limit the right of the Warrantholder
      right to pursue actual damages for any failure by the Company to comply
      with the terms of this Warrant.  The Company acknowledges that a breach
      by it of its obligations hereunder will cause irreparable harm to the
      Warrantholder and that the remedy at law for any such breach may be
      inadequate.  The Company therefore agrees that, in the event of any such
      breach or threatened breach, the Warrantholder shall be entitled, in
      addition to all other available remedies, an injunction restraining any
      breach, without the necessity of showing economic loss and without any
      bond or other security being required.
    

    
      Section 21.  Section Headings.  The section headings in
      this Warrant are for the convenience of the Company and the
      Warrantholder and in no way alter, modify, amend, limit or restrict the
      provisions hereof.
    

    
      [SIGNATURE PAGE FOLLOWS]
    

    
      
        

        

      

      
        
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      IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
      executed, as of the 11th day of August, 2008.
    

    
    	
           
        	
          
            OPEXA THERAPEUTICS, INC.
          

        
	

        	
           
        
	

        	
           
        
	

        	
          
            By: /s/Neil K. Warma
          

        
	

        	
          Neil K. Warma
        
	

        	
          President and Chief Executive Officer
        


    

    

    

    
      Signature Page to
Series F Warrant to Purchase ________
      Shares of
Common Stock, Par Value $0.50 Per Share
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
      APPENDIX A
    

    
      OPEXA THERAPEUTICS, INC.
    

    
      WARRANT EXERCISE FORM
    

    
      To Opexa Therapeutics, Inc.:
    

    
      The undersigned hereby irrevocably elects to exercise the right of
      purchase represented by the within Warrant (“Warrant”) for, and to
      purchase thereunder by the payment of the Warrant Price and surrender of
      the Warrant, _______________ shares of Common Stock (“Warrant Shares”)
      provided for therein, and requests that certificates for the Warrant
      Shares be issued as follows:
    

    
    	
           
        
	
          Name
        
	
           
        
	
           
        
	
          Address
        
	
           
        
	
          Federal Tax ID or Social Security No.
        


    

    
      and delivered by (certified mail to the above address, or
      (electronically (provide DWAC Instructions:________________), or (other
      (specify): ___________________________).  
    

    
      and, if the number of Warrant Shares shall not be all the Warrant Shares
      purchasable upon exercise of the Warrant, that a new Warrant for the
      balance of the Warrant Shares purchasable upon exercise of this Warrant
      be registered in the name of the undersigned Warrantholder or the
      undersigned’s Assignee as below indicated and delivered to the address
      stated below.
    

    
    	
          Dated: ___________________, ____
        	

        
	
          
            Note: The signature must correspond with
the name of the
            Warrantholder as written on
the first page of the Warrant in
            every
particular, without alteration or enlargement
or any
            change whatever, unless the Warrant has been assigned.
          

        	
          
            Signature:
          

        
	
           
        
	
          Name (please print)
        
	
           
        
	
           
        
	
          Address
        
	

        	
           
        
	

        	
          Federal Identification or Social Security No.
        
	

        	
           
        
	

        	
          Assignee:
        
	

        	
           
        
	

        	
           
        


    

    

    

    
      Appendix A
Warrant Exercise Form